U.S. patent application number 15/787218 was filed with the patent office on 2019-04-18 for infinitely variable power transmission system.
The applicant listed for this patent is Deere & Company. Invention is credited to G. William Detrick, Randall L. Long, Dwayne B. Watt.
Application Number | 20190113110 15/787218 |
Document ID | / |
Family ID | 66095688 |
Filed Date | 2019-04-18 |
United States Patent
Application |
20190113110 |
Kind Code |
A1 |
Watt; Dwayne B. ; et
al. |
April 18, 2019 |
INFINITELY VARIABLE POWER TRANSMISSION SYSTEM
Abstract
A power transmission system is disclosed for infinitely variable
speed capability. The power transmission system includes a pair of
power units, each configured to deliver a rotational torque to
drive an output element. A transmission arrangement receives the
rotational torques from the power units and delivers a resulting
torque to the output element. The transmission arrangement includes
a gear set coupling the one power unit to the output element to
deliver torque through a mechanical meshing engagement that is
continuously effected between the first power unit and the output
element.
Inventors: |
Watt; Dwayne B.;
(Bartlesville, OK) ; Detrick; G. William;
(Coffeyville, KS) ; Long; Randall L.;
(Coffeyville, KS) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Deere & Company |
Moline |
IL |
US |
|
|
Family ID: |
66095688 |
Appl. No.: |
15/787218 |
Filed: |
October 18, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F16H 2037/088 20130101;
B60K 6/08 20130101; F16H 3/72 20130101; A01D 69/06 20130101; F16H
37/084 20130101; B60Y 2200/222 20130101; A01D 46/08 20130101; F16H
47/04 20130101 |
International
Class: |
F16H 3/72 20060101
F16H003/72; B60K 6/08 20060101 B60K006/08 |
Claims
1. A power transmission system comprising: a first power unit
configured to deliver a first rotational torque; a second power
unit configured to deliver a second rotational torque; an output
element configured to be driven by the first and second power
units; and a transmission arrangement configured to receive the
first and second rotational torques and to deliver a resulting
torque to the output element, and including a gear set coupling the
first power unit to the output element; wherein the first
rotational torque is routed through the gear set, which is
configured so that a mechanical meshing engagement is continuously
effected between the first power unit and the output element.
2. The power transmission system of claim 1, wherein the gear set
is a planetary gear arrangement including: planet gears; a sun gear
through which the second rotational torque is received into the
transmission arrangement; and a carrier configured to carry the
planet gears in engagement with the sun gear and to deliver the
second rotational torque from the planetary gear arrangement to the
output element; wherein the first rotational torque is delivered to
the output element through the carrier.
3. The power transmission system of claim 2, wherein the planetary
gear arrangement does not include a ring gear encircling the planet
gears.
4. The power transmission system of claim 2, wherein the planet
gears each comprise a pair of pinion gears of different radii.
5. The power transmission system of claim 2, wherein the output
element is configured to rotate with the carrier.
6. The power transmission system of claim 2, wherein the gear set
includes a second sun gear and a second set of planet gears meshing
with the second sun gear.
7. The power transmission system of claim 6, wherein the second
planet gears are supported on the carrier.
8. The power transmission system of claim 1, wherein the first
power unit comprises an internal combustion engine configured to
operate at a constant speed, and the second power unit is
configured to provide a variable speed input to vary an output
speed of the output element.
9. The power transmission system of claim 8, further comprising a
harvesting unit coupled with the output element.
10. The power transmission system of claim 8, wherein the second
power unit is configured as a hydraulic motor.
11. The power transmission system of claim 10, further comprising a
hydraulic pump driven by the internal combustion engine, the
hydraulic pump configured to supply fluid to drive the hydraulic
motor.
12. A power transmission system comprising: a first power unit
configured to deliver a first rotational torque; a second power
unit configured to deliver a second rotational torque; an output
element configured to be driven by the first and second power
units; and a transmission arrangement configured to receive the
first and second rotational torques and to deliver a resulting
torque to the output element, and the transmission arrangement
including: a first input gear driven by the first power unit, the
transmission arrangement configured to provide a mechanical meshing
engagement that is continuously effected between the first input
gear and the output element; and a second input gear driven by the
second power unit at variable speeds, the transmission arrangement
configured to combine the first and second rotational torques to
drive the output element at the resulting torque.
13. The power transmission system of claim 12, wherein the second
power unit is reversible to effect variable forward speeds and
variable reverse speeds of the output element.
14. The power transmission system of claim 12, wherein the second
power unit is configured to provide a zero output speed to the
output element by driving the second input gear in a direction
relative to the first input gear that is opposite and at a speed
that offsets the first power unit so that the output element is
held from rotating.
15. The power transmission system of claim 12, wherein the first
and second input gears are configured as sun gears; and wherein the
transmission arrangement further includes: first planet gears
meshing with the first input gear: and second planet gears meshing
with the second input gear; wherein the first planet gears each
have a first pinion gear and a second pinion gear, and the second
planet gears each have a third pinion gear and a fourth pinion
gear, the first and fourth pinion gears meshing together.
16. The power transmission system of claim 15, wherein the first
and second planet gears are not encircled by a ring gear.
17. The power transmission system of claim 12, wherein the
transmission arrangement is configured to route the first and
second rotational torques from the first and second power units to
the output element without the use of a clutch.
18. A power transmission system comprising: first and second power
units; a transmission arrangement coupling the first and second
power units with an output element and including: a first input
gear driven by the first power unit, the transmission arrangement
configured to provide a mechanical meshing engagement that is
continuously effected between the first input gear and the output
element; and a second input gear configured to be driven by the
second power unit at variable speeds and directions; wherein the
transmission arrangement is configured to effect variable forward
speeds of the output element, a zero output speed of the output
element, and variable reverse speeds of the output element.
19. The power transmission system of claim 18, wherein the
transmission arrangement is configured to provide the zero output
speed when the output element is stopped, while the first power
unit drives the first input gear at a speed that is constant.
20. The power transmission system of claim 18, wherein the first
and second input gears are configured as sun gears; and wherein the
transmission arrangement further includes: first planet gears
meshing with the first input gear; and second planet gears meshing
with the second input gear; wherein the first planet gears each
have a first pinion gear and a second pinion gear, and the second
planet gears each have a third pinion gear and a fourth pinion
gear, the first and fourth pinion gears meshing together.
Description
CROSS-REFERENCE TO RELATED APPLICATION(S)
[0001] Not applicable.
STATEMENT OF FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] Not applicable.
FIELD OF THE DISCLOSURE
[0003] This disclosure relates to power transmissions, including
transmission systems for powering work vehicles and machinery with
infinitely variable speed capability.
BACKGROUND OF THE DISCLOSURE
[0004] An infinitely variable transmission (IVT) is a type of
automatic transmission that changes seamlessly through a continuous
range of effective gear ratios. In particular, an IVT produces
ratios of output shaft speed to input shaft speed through a speed
range that includes a zero ratio, which provides a zero output
speed. IVTs may be used in a variety of applications including for
vehicle propulsion and machinery drive purposes.
[0005] Vehicles may be configured such that various components,
including ground drive and harvesting components, may be driven by
a power source using an IVT. For example, in a harvester, an engine
may power a ground drive and various harvesting units. This may be
useful, for example, to provide variable control over the operating
speeds of the ground drive arid the harvesting units.
SUMMARY OF THE DISCLOSURE
[0006] According to one aspect of the disclosure, a power
transmission system includes a pair of power units, each configured
to deliver a rotational torque to drive an output element. A
transmission arrangement receives the rotational torques from the
power units and delivers a resulting torque to the output element.
The transmission arrangement includes a gear set coupling one power
unit to the output element to deliver torque through a mechanical
meshing engagement that is continuously effected between the first
power unit and the output element.
[0007] In certain embodiments, the transmission arrangement of a
power transmission system includes a planetary gear arrangement
that does not include a ring gear encircling the planet gears.
[0008] According to another aspect of he disclosure, a power
transmission system includes a pair of power units that deliver
rotational torque to drive an output element. A transmission
arrangement receives the rotational torque from the power units and
delivers a resulting torque to the output element. The transmission
arrangement includes an input gear driven by one power unit
providing a continuous mechanical meshing engagement between the
input gear and the output element. Another input gear is driven by
the other power unit at variable speeds. The transmission
arrangement combines the torques from the input gears to drive the
output element at the resulting torque.
[0009] According to still another aspect of the disclosure, a power
transmission system includes a pair of power units. A transmission
arrangement couples the power units with an output element. The
transmission arrangement includes an input gear driven by one of
the power units to provide a continuous mechanical meshing
engagement between the input gear and the output element. Another
input gear is driven by the other power unit at variable speeds and
directions so that the transmission arrangement effects variable
forward speeds of the output element, a zero output speed of the
output element, and variable reverse speeds of the output
element.
[0010] The details of one or more implementations are set forth in
the accompanying drawings and the description below. Other features
and advantages will become apparent from the description, the
drawings, and the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a side view of an example harvesting vehicle,
configured as a cotton picker;
[0012] FIG. 2 is a schematic view of an example power transmission
arrangement, such as for the harvesting units of the harvesting
vehicle of FIG. 1;
[0013] FIG. 3 is a schematic view of another example power
transmission arrangement, such as for the harvesting units of the
harvesting vehicle of FIG. 1; and
[0014] FIG. 4 is a schematic view of another example power
transmission arrangement, such as for the harvesting units of the
harvesting vehicle of FIG. 1
[0015] Like reference symbols in the various drawings indicate like
elements.
DETAILED DESCRIPTION
[0016] The following describes one or more example embodiments of
the disclosed power transmission system, as shown in the
accompanying figures of the drawings described briefly above.
Various modifications to the example embodiments may be
contemplated by one of skill in the art.
[0017] As used herein, "between" may be indicate the relationship
of various components along a power-transmission path, rather than
necessarily the relationship of various components in physical
space. In this regard, a power transmission component may be viewed
as being "between" two other components if power may flow between
the two other components via the power transmission component, even
if it is not disposed in the physical space separating the two
components. For example, if power is transmitted in one direction
from a power source to a gear arrangement, and is then routed by
the gear arrangement to a working unit by an output element that
extends past the power source in a second direction, the gear
arrangement and the output element may be viewed as being "between"
the power source and the working unit even though the gear
arrangement (and part of the output element) may not occupy the
physical space separating the power source and the working
unit.
[0018] In various examples discussed below, particular arrangements
of power transmission elements, shafts, gears, clutches, and other
components may be presented. It will be understood that various
alternative (or additional) configurations of such power
transmission elements, shafts, gears, clutches, or other components
may be utilized without departing from the teachings of this
disclosure. For example, a single shaft in various embodiments may
be replaced, in other embodiments, with an arrangement of multiple
shafts (e.g., multiple coaxial shafts, or multiple offset shafts
connected by various gear arrangements). Likewise, a particular
arrangement of multiple shafts in certain embodiments may be
replaced (or supplemented), in other embodiments, with a different
arrangement of multiple (or individual) shafts. For example, an
arrangement of parallel shafts may be replaced (or supplemented)
with an arrangement of nested, coaxial shafts (e.g., one hollow
shaft surrounding another coaxial shaft). Further, a connection
including a particular number or arrangement of gears in certain
embodiments may be replaced with a connection including a different
number or arrangement of gears in other embodiments. For example, a
meshing engagement between two gears to transmit power between
those gears may be replaced by a meshing between the two gears,
respectively, and a number of idler gears, in order also to
transmit power between the two gears. Further, in certain
embodiments, various example clutches may be replaced (or
supplemented) with other selective engagement mechanisms configured
to provide similar power-transmission states.
[0019] It will further be understood that various changes in the
direction of power transmission (or the rotational direction of
transmitted power) may be accomplished using various alternative
arrangements. As such, embodiments depicting transmission of power
in a particular direction are not presented to the exclusion of
similar (or other) embodiments transmitting power in other
directions. For example, various embodiments below may present
transmission of power from an engine to a working unit with
generally parallel rotation of the various power-transmitting
components (e.g., various shafts and gears). It will be understood,
however, that components of certain working units may operate via
rotation around an axis that is not parallel with an axis of
rotation of output power from the engine (or another power source).
As such, although parallel rotation may be depicted in various
embodiments, various known arrangements (e.g., bevel gear
arrangements, universal joints, constant-velocity joints, and so
on) may be utilized to provide rotational power to (or within) a
working unit along a different rotational axis than the power
output from the engine or other power source.
[0020] In one or more example implementations of the disclosed
power transmission system, infinitely variable output speeds are
provided through a split power path with dual inputs. Generally,
the disclosed infinitely variable power transmission system
provides seamless transition through forward speed ratios, a zero
speed ratio, and reverse speed ratios, with improved efficiency. In
certain embodiments, one input is provided via a constant speed
power source for maximum efficiency and the other input is provided
by a variable speed power source to provide an infinitely variable
output speed.
[0021] The following description relates to a power transmission
system that may be described in the context of a work vehicle, and
in particular a cotton picker application with harvesting units as
working units, for purposes of demonstrating an example. During
operation, it may be useful to control the operating speeds of the
harvesting units of the cotton picker. For example, to effectively
gather cotton from a field during harvesting, it may sometimes be
useful to vary operating speeds of the harvesting units in
proportion to the ground speed of the harvester. Under other
conditions, the harvesting units may be operated at a speed
independent of the ground speed of the harvester, such as in
relation to the density of the crop.
[0022] The present disclosure is not limited to cotton picker
harvester unit drive applications or to harvesters in general, but
rather, also encompasses any application where infinitely variable
output is desired, including those where zero speed output is
required. Accordingly, the teachings of the present disclosure are
applicable to power transmission systems in a variety of
applications, such as work vehicle propulsion drives, machinery and
equipment drives, power take-off systems, power generator drives,
and others.
[0023] In an example of the present disclosure as further described
below, a power transmission system includes a first power unit
delivering a first rotational torque and a second power unit
delivering a second rotational torque to drive an output element. A
transmission arrangement receives the first and second rotational
torques and delivers a resulting torque to the output element. The
transmission arrangement includes a gear set coupling the first
power unit to the output element and through which, the first
rotational torque is routed. The combination of gears and other
torque transmission elements provides a mechanical meshing
engagement that is continuously effected between the first power
unit and the output element.
[0024] As noted above, the power transmission system described
herein may be employed in a variety of applications. Referring to
FIG. 1, one example involves a cotton picker 20, depicted with a
power transmission system 22 for transmitting power from a power
source in the form of an engine 24 of the cotton picker 20, to a
set of forward harvesting units 28 for gathering cotton. As
depicted, harvesting units 28 include various drums 30, which
rotate during operation of the harvesting units 28 to pull fiber
and seed from cotton plants. Cotton gathered by the harvesting
units 28 is moved by air pressure through a duct arrangement 32
into the body 34 of the cotton picker 20 (e.g., for forming into
bales). In the configuration depicted, and as discussed in greater
detail below, the harvesting units 28 receive operating power from
the engine 24 via the power transmission system 22. As depicted,
for example, each individual harvesting unit 28 (or a set of
multiple harvesting units 28) may be mechanically powered by a
corresponding drive shaft 36 extending from the power transmission
system 22 to the harvesting unit 28. In other embodiments, a
different arrangement (e.g., an arrangement of various shafts,
gears or other torque transmitting elements) may be utilized to
communicate power from various power sources to the harvesting
units 28. In the current example the engine 24 provides the power
source as an internal combustion engine. In other examples, the
power source may be an electric motor, a hybrid drive system, or
another alternative powertrain source.
[0025] The engine 24 may also be used to power the wheels 26 to
propel the cotton picker 20 through a drive system (not shown). The
cotton picker 20 may include various other devices and systems. As
depicted, for example, the cotton picker 20 includes a controller
38. The controller 38 may be configured in a variety of ways,
including as an electronic computing device with one or more
processors and memory architectures, as a programmable electronic
circuit, or otherwise. In certain embodiments, the controller 38
may be disposed at other locations, including locations remotely
located from the cotton picker 20. In certain embodiments, multiple
controllers may be utilized. For example, the controller 38 may be
configured as a transmission control unit for controlling operation
of various devices of the power transmission system 22, and another
controller (not shown) may be configured as an engine control unit
for controlling operation of the engine 24.
[0026] Referring also to FIG. 2, the power transmission system 22
includes an example embodiment of a transmission arrangement 40 for
use with the cotton picker 20 (or other work vehicles). In the
embodiment depicted, power from the power source in the form of the
engine 24 is delivered to the power transmission system 22 by an
input shaft 44, which is continuously driven to rotate when the
engine 24 is operating. In this example, the engine 24 is an
internal combustion engine and is operated at a constant speed
selected to maximize efficiency. For example, the engine 24 is
operated at the speed of highest brake specific fuel consumption
efficiency for the application's load. Accordingly, the input shaft
44 may rotate at a constant speed appropriate for the load during a
given operating mode of the transmission arrangement 40. In some
examples the engine 24 operates at a constant speed across multiple
or all operating modes. In general, the engine 24 as the power
source delivers a rotational torque to the transmission arrangement
40 through the input shaft 44. In this example, the rotational
torque is delivered through the transmission arrangement 40 to an
output element 50, and is used to drive the harvesting units 28
using mechanical energy delivered by the engine 24 in an efficient
manner.
[0027] Another power source 46 provides power to the transmission
arrangement 40 through another input shaft 48. In general, the
second power source 46 provides another rotational torque input to
the transmission arrangement 40. When the input provided by the
power source 46 is summed with the input delivered from the engine
24, infinitely variable speeds of an output element 50 are
effected, as further detailed below. In addition, the transmission
arrangement 40 may be configured to provide for reverse-direction
operation of the harvesting units 28 as further detailed below.
This may be useful, for example, in order to clear material that
has accumulated in the harvesting units 28, or for other
reasons.
[0028] In the current example, the power source 46 includes a
hydraulic motor 47 that converts hydraulic pressure arid flow into
torque arid rotation. For example, the hydraulic motor 47 may be a
gear and vane, gerotor, axial plunger or radial piston type of
hydraulic motor. In the current example the hydraulic motor 47 is
reversible. The hydraulic motor 47 receives hydraulic pressure and
flow through various conduits from a variable displacement
hydraulic pump 52, such as an axial piston pump or a variable vane
pump. Accordingly, the torque and rotation supplied to the input
shaft 48 is varied by varying the displacement of the hydraulic
pump 52 to change the output from the hydraulic motor 47. The
hydraulic pump 52 is provided with power from the engine 24 such as
through a shaft 54. In other examples, the power source 46 may be
any variable drive mechanism such as an electric motor or
mechanically driven device. It will be understood that the power
source 46 may include various additional hydraulic devices such as
valves, regulators, a reservoir, or others, which are omitted form
the illustration for simplicity.
[0029] The input shaft 48 is coupled with a gear set 56 forming a
planetary gear arrangement, which in this example is connected in a
compound planetary configuration. The input shaft 48 is connected
with a sun gear 58 of the gear set 56. A number of planet gears 60,
62 are disposed around the sun gear 58 and are in meshed engagement
therewith. In FIG. 2 two planet gears 60, 62 are shown but another
number of individual planet gears may be included and all may be
equally spaced around the sun gear 58. The planet gears 60, 62 are
constructed in the form of composite planet gears, each with a pair
of pinions 64, 66 and 68, 70, respectively. The pinions 64, 66 are
paired together as rigidly connected gears that are longitudinally
arranged to rotate together about a common axis, and may have
different radii and/or different numbers of teeth. Similarly, the
pinions 68, 70 are paired together as rigidly connected gears that
are longitudinally arranged to rotate together about a common axis,
and may have different radii and/or different numbers of teeth.
Accordingly, the element that meshes with the pinion 64 or 68 may
rotate at a different speed as compared to the element that meshes
with the pinion 66 or 70, respectively. In this example, one of
each pair of pinions engages the sun gear 58 and is driven thereby.
Specifically, pinions 64 and 68 mesh with, and are driven by, the
sun gear 58. The planet gears 60, 62 are rotationally arranged on a
carrier 72, which is disposed in the transmission arrangement 40 to
rotate.
[0030] Returning to the power source provided by the engine 24, the
input shaft 44 is coupled with a gear set 74, which forms a
planetary gear arrangement. In this example the input shaft 44 is
connected with a sun gear 76 of the gear set 74. A number of planet
gears 78, 80 are disposed around the sun gear 76 and are in meshed
engagement therewith. In FIG. 2 two planet gears 78, 80 are shown
but another number of individual gears may be included and all may
be equally spaced around the sun gear 76. The planet gears 78, 80
are in the form of composite planet gears, each with pair of
pinions 82, 84 and 86, 88, respectively. The pinions 82, 84 are
paired together as rigidly connected gears that are longitudinally
arranged to rotate together about a common axis, and may have
different radii and/or different numbers of teeth. Similarly, the
pinions 86, 88 are paired together as rigidly connected gears that
are longitudinally arranged to rotate together about a common axis,
and may have different radii and/or different numbers of teeth.
Accordingly, the element that meshes with the pinion 82 or 86 may
rotate at a different speed as compared to the element that meshes
with the pinion 84 or 88, respectively. One of each pair of pinions
engages the sun gear 76 arid is driven thereby. In this example,
pinions 84 and 88 mesh with the sun gear 76 and are driven thereby.
The planet gears 78, 80 are rotationally arranged on the carrier
72, along with the planet gears 60, 62. One of each pair of pinions
of the planet gears 78, 80 engages a respective one of the pinions
of the planet gears 60, 62. In this example, pinions 82, 86 mesh
with pinions 66, 70 respectively, providing the compound planetary
configuration in the transmission arrangement 40. Meshing
engagement between the planet gears 60, 62 and the planet gears 78,
80 respectively, provides a coupling between the two power sources,
namely, the engine 24 and the hydraulic motor 47/hydraulic pump 52,
so that their inputs are combined in driving the carrier 72 to
rotate. In this example, the gear sets 56, 74 do not include ring
gears that would otherwise encircle and mesh with the planet gears,
saving in cost and weight of the transmission arrangement 40. To
effectively and efficiently transfer torque to the output element
50, a reaction force is established for the input provided by the
hydraulic motor 47 against the torque supplied by the engine 24 via
the meshed engagement of the planet gears 60, 62 and 78, 80
respectively, which enables achieving very slow to no speed output
at the output element 50, without the use of clutches or brakes in
the transmission arrangement 40. Specifically, no clutch or brake
is required in the power paths between the input shafts 44, 48 and
the output element 50.
[0031] Returning to the carrier 72, in this example it includes
pins 90, 92, which are a fixed part of the carrier 72 on which the
planet gears 60, 62 respectively, are rotationally mounted. The
carrier 72 also includes pins 94, 96, which are a fixed part of the
carrier 72 on which the planet gears 78, 80 are rotationally
mounted. The carrier 72 includes a gear 98 which is configured to
rotate with the carrier 72 and may be an integral part thereof, or
a separate connected piece. The gear 98 meshes with a gear 100,
which is configured to rotate with the output element 50 and may be
an integral part thereof, or a separate connected piece. As such,
rotation of the carrier 72 drives the output element 50 through the
gears 98, 100. A clutch 102, or another selective engagement
mechanism may be disposed between the gear 100 and the harvesting
units 28 for selectively connecting or disconnecting the harvesting
units 28 from the transmission arrangement 40, when desired. The
clutch 102 may include various other devices and components (not
shown), including control electronics, hydraulic lines and control
systems, various shafts or gears, and others. In other examples
where disconnecting the working units is not needed, the clutch 102
may be omitted.
[0032] To operate the harvesting units 28, the clutch 102 is
engaged with the engine 24 operating. It will be understood that
the power source 46 is also operated, as further described below.
The engine 24 drives the input shaft 44, rotating the sun gear 76.
The sun gear 76 drives the relatively smaller planet gears 78, 80
to rotate, applying a force to the pins 94, 96 causing the carrier
72 to rotate. The gear 98 is driven to rotate with the carrier 72
causing the gear 100 and output element 50 to rotate, driving the
harvesting units 28 through the clutch 102. As noted above, the
engine 24 may be operated at a constant speed for efficiency
purposes. The constant speed may be the same for all operating
modes of the power transmission system 22, or may be selected to
provide different constant speeds for different operating modes of
the power transmission system 22. For example, if different modes
exist with significantly different torque requirements, different
constant speeds of the engine 24 may be used for each of those
different torque requirements to maximize efficiency. This enables
maintaining efficient operation of the engine 24 in applications
including those with constant torque requirements and also in
applications with changing torque requirements. In either case, the
majority of the torque required may be supplied by the engine 24 as
the primary power source. The power source 46 may then provide
input to vary the speed of the output element 50 through its power
path, which includes the gear set 74. The hydraulic motor 47 of the
power source 46 may be operated to increase or decrease the
rotational speed of the carrier 72, and therefore that of the
output element 50, and to reverse directions. For example, when the
hydraulic motor 47 is operated, the input shaft 48 and the sun gear
58 rotate. The sun gear 58 drives the relatively smaller planet
gears 60, 62 to rotate, applying a force to the pins 90, 92 causing
the carrier 72 to rotate. With the effect on the carrier 72 from
the planet gears 60, 62 added to the effect on the carrier 72 from
the planet gears 78, 80, the gear 98 is driven to rotate with the
carrier 72 causing the gear 100 and output element 50 to rotate,
driving the harvesting units 28 through the clutch 102. The
hydraulic motor 47 may be operated to increase the speed of the
carrier 72 as compared to the speed achieved from the engine 24
alone, or to decrease the speed of the carrier 72, including to
achieve very low speeds or zero speed. The speed varying
relationship of the transmission arrangement 40 is represented by
the equation:
n 72 = n 44 + n 48 ( N 58 * N 66 * N 84 N 64 * N 82 * N 76 ) 1 + (
N 58 * N 66 * N 84 N 64 * N 82 * N 76 ) ##EQU00001##
where:
[0033] n.sub.72 is the speed of the carrier 72, in rpm;
[0034] n.sub.44 is the speed of the input shaft 44, in rpm;
[0035] n.sub.48 is the speed of the input shaft 48, in rpm;
[0036] N.sub.58 is the gear tooth count of the sun gear 58;
[0037] N.sub.64 is the gear tooth count of the pinion 64;
[0038] N.sub.66 is the gear tooth count of the pinion 66;
[0039] N.sub.78 is the gear tooth count of the sun gear 76;
[0040] N.sub.82 is the gear tooth count of the pinion 82; and
[0041] N.sub.84 is the gear tooth count of the pinion 84.
[0042] Through the example of the transmission arrangement 40, the
output element 50 is driven in an infinitely variable manner with
input from dual power sources and a split power path that is joined
through the carrier 72. One of the power sources is an engine 24 in
the example, which provides a mechanical drive power path that may
delver a majority of the torque for the output element 50. This
enables providing more torque at the output element 50 as compared
to hydraulic drive alone, which translates to advantages such as
greater bale density in the example of the cotton picker 20. The
mechanical drive power path provides efficiency gains over
hydraulic drive by allowing the engine to operate at its peak
efficiency, and by avoiding hydraulic losses such as those
encountered in transitions between hydraulic and mechanical
components, fluid transmission losses, and pumping losses. As a
result, more power of the engine may be available for other uses in
the work vehicle or other application. High overall system
efficiency is achieved by minimizing the power flow through the
variable speed sun gear 58. Efficient operation is optimized in the
normal operating range of the harvester units 28 by the prudent
selection of gear ratios and other input drive components. The
speed of the output element 50 is a sum of the speeds of the input
shafts 44, 48 and is a function of the sun gears 58, 76, and of the
pinions 64, 66, 82 and 84. It will be appreciated that the pinions
68, 70, 86 and 88 (and those of any additional planet gears), do
not change the speed contribution of the pinions identified in the
above equation, but act to distribute the loads around the gear
sets 56, 74.
[0043] Referring to FIG. 3, the power transmission system 22 is
constructed in an example with a transmission arrangement 110
having a simplified planetary configuration. The input shaft 44 is
again driven by a power source in the form of the engine 24 and the
input shaft 48 is driven by the power source 46 with the hydraulic
motor 47 and the hydraulic pump 52. The hydraulic pump 52 is again
driven by the engine 24 through the shaft 54. The transmission
arrangement 110 drives the harvesting units 28 through the output
element 50, the clutch 102 and the drive shaft 36. In this example,
the input shaft 48 is coupled with a gear set 112, which forms a
planetary gear arrangement. The input shaft 48 is connected with a
sun gear 114 of the gear set 112. A number of planet gears 116, 118
are disposed around the sun gear 114 and are in meshed engagement
therewith. In FIG. 3 two planet gears 116, 118 are shown but
another number of individual gears may be included and all may be
equally spaced around the sun gear 114. In this example, the planet
gears 116, 118 are encircled by a ring gear 120 and are in meshed
engagement therewith. The planet gears are mounted on a carrier 122
and are rotationally disposed on pins 124, 126, respectively. The
carrier 122 is configured to rotate with the output element 50 and
the two may be formed as one piece or as separate connected
parts.
[0044] In this example, the input shaft 44 is connected with a gear
128 which meshes with another gear 130. The gear 130 is connected
with the ring gear 120 and the two may be formed as one piece or as
separate connected parts. The input shaft 48 passes through the
center of the gear 130 and the two rotate about a common axis. The
engine 24 mechanically drives the carrier 122 and the output
element 50 through the input shaft 44, the gears 128, 130, the ring
gear 120 and the planet gears 116, 118. The engine 24 may be
operated at a constant speed at its peak efficiency and the
rotational speed of the output element 50 may be infinitely varied
through additional operation of the power source 46. The hydraulic
motor 47 may be operated to reversibly drive the input shaft 48
through the power path of the sun gear 114, the planet gears 116,
118, and the carrier 122. The transmission arrangement 110 sums the
inputs of input shafts 44, 48 and provides the resulting output
through the carrier 122 to the output element 50.
[0045] Referring to FIG. 4, the power transmission system 22 is
constructed with a transmission arrangement 134 having a compound
planetary configuration. The input shaft 44 is again driven by a
power source in the form of the engine 24 and the input shaft 48 is
driven by the power source 46 with the hydraulic motor 47 and the
variable displacement hydraulic pump 52. The hydraulic pump 52 is
again driven by the engine 24 through the shaft 54. The
transmission arrangement 134 drives the harvesting units 28 through
the output element 50 and the clutch 102. In this example, the
input shaft 48 is coupled with a gear set 136, which forms a
planetary gear arrangement. The input shaft 48 is connected with a
sun gear 138 of the gear set 136. A number of planet gears 140, 142
are disposed around the sun gear 138 and are in meshed engagement
therewith. In FIG. 4, two planet gears 140, 142 are shown but
another number of individual gears may be included and all may be
equally spaced around the sun gear 138. The planet gears 140, 142
are in the form of composite planet gears, each with pair of
pinions 144, 146 and 148, 150, respectively. The pinions 144, 146
are paired together as rigidly connected gears that are
longitudinally arranged to rotate together about a common axis, and
may have different radii and/or different numbers of teeth.
Similarly, the pinions 148, 150 are paired together as rigidly
connected gears that are longitudinally arranged to rotate together
about a common axis, and may have different radii and/or different
numbers of teeth. One of each pair of pinions meshes with the sun
gear 138 and is driven thereby. In this example, pinions 144, 148
mesh with the sun gear 138 and are driven thereby. The planet gears
140, 142 are rotationally arranged on a carrier 154, which is
rotationally disposed in the transmission arrangement 134.
[0046] In the example of FIG. 4, the planet gears 140, 142 are
encircled by a ring gear 152 and are in meshed engagement therewith
through the pinions 144, 148. The planet gears 140, 142 are mounted
on a carrier 154 and are rotationally disposed on pins 156, 158,
respectively. The carrier 154 is configured to rotate with the
output element 50 and the two may be formed as one piece or as
separate connected parts.
[0047] In this example, the input shaft 44 is connected with a gear
160 through a clutch 162. The clutch 162 provides an engagement
mechanism for selectively connecting or disconnecting the engine 24
from the transmission arrangement 134. The gear 160 meshes with
another gear 164. The gear 164 is connected with the ring gear 152
and the two may be formed as one piece or as separate connected
parts. The input shaft 48 passes through the center of the gear 164
and the two rotate about a common axis. The engine 24 mechanically
drives the carrier 154 and the output element 50 through the input
shaft 44, the clutch 162, the gears 160, 164, the ring gear 152 and
the planet gears 140, 142. The engine 24 may be operated at a
constant speed at its peak efficiency and the rotational speed of
the output element 50 may be infinitely varied through operation of
the power source 46. The hydraulic motor 47 may be operated to
reversibly drive the input shaft 48 through a power path that
includes the sun gear 138, the planet gears 140, 142, and the
carrier 154. The transmission arrangement 134 sums the input at the
input shaft 44 and the input shaft 48, and provides the resulting
output through the carrier 154 to the output element 50.
[0048] The transmission arrangement 134 includes a compound
planetary configuration with another set of planet gears, including
planet gears 168, 170 in meshing engagement with the pinions 146,
150 respectively. The planet gears 168, 170 are mounted on the
carrier 154 and are rotationally disposed on pins 172, 174
respectively. A ring gear 176 encircles the planet gears 168, 170
and is in meshing engagement therewith. The ring gear 176 is
selectively coupled with a case 178 (which does not rotate),
through a torque transfer element 180 and a brake 182. In this
example, the torque transfer element 180 is in the form of an
annular rotor and may be formed together with the ring gear 176 as
one piece, or the two may be separate connected parts. To provide
very low to zero speeds of the output element 50, the engine 24 is
disconnected from the transmission arrangement 134 by disengagement
of the clutch 162, and the ring gear 176 is connected with the case
178 by engagement of the brake 182. This provides a second reaction
for the transmission arrangement 134 along with the input of the
power source 46 through the input shaft 48, when the engine is
disconnected.
[0049] Through the examples described above, a power transmission
system delivers infinitely variable output speeds through a split
power path with dual power source inputs. The disclosed infinitely
variable power transmission system includes a transmission
arrangement that provides seamless transition through forward speed
ratios, a zero output speed, and reverse speed ratios, with
improved efficiency. In certain embodiments, one input is provided
via a constant speed power source for maximum efficiency and the
other input is provided by a variable speed power source to provide
an infinitely variable output speed.
[0050] The terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting of
the disclosure. As used herein, the singular forms "a", "an" and
"the" are intended to include the plural forms as well, unless the
context clearly indicates otherwise. It will be further understood
that any use of the terms "comprises" and/or "comprising" in this
specification specifies the presence of stated features, integers,
steps, operations, elements, and/or components, but do not preclude
the presence or addition of one or more other features, integers,
steps, operations, elements, components, and/or groups thereof.
[0051] The description of the present disclosure has been presented
for purposes of illustration and description, but is not intended
to be exhaustive or limited to the disclosure in the form
disclosed. Many modifications and variations will be apparent to
those of ordinary skill in the art without departing from the scope
and spirit of the disclosure. Explicitly referenced embodiments
herein were chosen and described in order to best explain the
principles of the disclosure and their practical application, and
to enable others of ordinary skill in the art to understand the
disclosure and recognize many alternatives, modifications, and
variations on the described example(s). Accordingly, various other
implementations are within the scope of the following claims.
* * * * *